The present invention relates to hydraulic vibration-damping supports including clip-on decoupling flaps and serving, for example, for mounting the engine-and-gearbox unit of a vehicle on the body of the vehicle.
More particularly, the invention relates to a hydraulic vibration-damping support designed to be interposed between two rigid elements (e.g. an engine-and-gearbox unit of a vehicle and the body of said vehicle) for damping and interconnection purposes, said support comprising:
two rigid strength members designed to be connected to respective ones of the two rigid elements to be interconnected;
an elastomer body connecting together the two strength members;
a working chamber filled with liquid and defined in part by the elastomer body;
a flexible elastomer wall which is secured to the second strength member;
a compensation chamber filled with liquid and defined in part by the flexible elastomer wall;
a constricted passage filled with liquid and which puts the working chamber into communication with the compensation chamber;
a rigid partition separating the working chamber from the compensation chamber, said rigid partition being provided with at least first and second gratings, each of which has a plurality of liquid-passing holes, the gratings defining between them a housing, the liquid-passing holes of one of the first and second gratings putting said housing into communication with the working chamber, and the liquid-passing holes of the other of the first and second gratings putting said housing into communication with the compensation chamber; and
a decoupling flap made of elastomer and comprising a pad which has first and second faces facing respective ones of the first and second gratings, said pad being mounted with a small amount of clearance (at least over a portion of its surface area) between said gratings, and said decoupling flap further comprising a first elastomer fastening member which projects from the first face of the pad, said first fastening member being fixed to the first grating by being clipped thereto, with clearance sufficient to enable said pad to move between the two gratings.
Document FR-A-2 751 042 describes an example of such a vibration-damping support which is quite satisfactory as regards technical operation.
In vibration-damping supports of the type described in that document, the decoupling flap is clipped to the first grating only, by means of said first fastening member, engaged resiliently in a hole in said first grating that is provided specifically for that purpose, and that does not allow liquid to pass through it.
The first fastening member can turn inside the hole in question, so that that assembly configuration does not set the angular position of the decoupling flap about its central axis.
In practice, that freedom of movement thus makes it necessary to give the decoupling flap a shape that is symmetrical about an axis, which is not always the best solution.
A particular object of the present invention is to mitigate that drawback.
To this end, in a vibration-damping support of the type in question the decoupling flap further comprises a second fastening member which projects from the first face of the pad, said first and second fastening members being clipped into respective ones of two liquid-passing holes in the first grating, while leaving said liquid-passing holes unobstructed in part.
By means of these provisions, the decoupling flap is positioned properly relative to the gratings of the rigid partition, which makes it possible to give the flap and the gratings any outline, and in particular an outline that is not symmetrical about an axis.
The decoupling flap can thus be clipped to the first grating before the vibration-damping support is fully assembled, thereby simplifying the assembly process, because no concern needs to be given to the positioning of the decoupling flap during said assembly process. This is even more important since the assembly process in question is usually performed in a bath of liquid to guarantee that the hydraulic vibration-damping support is filled properly with said liquid, so that said assembly process is relatively difficult to implement.
Finally, it should be noted that the two fastening members of the decoupling flap are clipped into two liquid-passing holes, so that it is no longer necessary to provide dedicated clipping holes for the sole purpose of clipping the decoupling flap. The gratings of the rigid partition are thus simpler to manufacture.
In preferred embodiments of the invention, it is optionally possible, in addition, to use any of the following provisions:
the first and second fastening members are fixed to the first grating with clearance that is sufficient to enable the pad to move between the two gratings;
the decoupling flap has a shape that is not circularly symmetrical about a central axis that is perpendicular to the pad of said decoupling flap;
the fastening members co-operate with the first grating to hold the decoupling flap stationary without clearance parallel to the pad;
each of the first and second fastening members comprises firstly a body that passes through the corresponding liquid-passing hole and that is in abutment against an uninterrupted portion of the first grating that defines said liquid-passing hole, and secondly a head which overlaps in part said uninterrupted portion of the first grating;
the heads of the first and second fastening members project towards each other from the bodies of said first and second fastening members;
the liquid-passing holes of the first grating are distributed angularly about a central axis, and each of them has a wedge-shaped portion in the vicinity of said central axis, the bodies of the first and second fastening members being in abutment against said uninterrupted portion of the first grating at the wedge-shaped portions of the corresponding liquid-passing holes;
the bodies of the first and second fastening members have portions adapted to fit closely to said wedge-shaped portions of the corresponding liquid-passing holes; and
the pad has a central portion from which the fastening members extend, the first and second faces of the pad having convex shapes, and the pad having its maximum thickness at said central portion.